Wet weather leads to boom in mosquito population

Pesky insect's population booming in wake of rains, but West Nile threat remains low — for now

Excessive rain and a string of warm days over the past two weeks have contributed to a surge in the mosquito population across Chicagoland, health officials say.

The northern and western suburbs are stepping up efforts to battle what officials are calling record mosquito infestations, while their counterparts in southern Cook County are facing mosquito levels maybe three times higher than in recent memory.

"This is the worst mosquito outbreak in 20 years," said Laura McGowan, a spokeswoman for Clarke Environmental Mosquito Management of Roselle, which handles abatement for several communities in western DuPage County. "The (mosquito) traps are catching three to four times the amount that's usually considered a nuisance."

Traps that typically capture a couple hundred mosquitoes are filling up with thousands, McGowan said.

Abatement officials in the North Shore communities of Evanston, Wilmette and Glencoe are calling the mosquito populations unprecedented. Residents in Schaumburg, Palatine and Wheeling say they're being "eaten alive" even after applying insect repellent.

"With the numbers (of mosquitoes) we're seeing now out there, if you miss one patch of skin they will find it," said Mike Szyska, director of the Northwest Mosquito Abatement District.

The good news is that the heavy rains that have doused the Chicago area this summer don't typically produce the kinds of mosquitoes known to carry the deadly West Nile virus, said Linn Haramis, an entomologist with the Illinois Department of Public Health. The "Flood-water" mosquitoes that are so prevalent are aggressive biters, he said, but are not considered a health threat.

But as the temperature rises and the air becomes dryer, health officials worry about an explosion in the number of northern house mosquitoes that carry West Nile virus, an airborne disease blamed in the deaths of dozens of Illinois residents since 2002. Though the number of West Nile cases has steadily declined in Illinois and around the country over the past eight years, weather conditions will determine if it remains that way, Haramis said.

"We're in that period where if you're outside, and even if you don't see mosquitoes in your neighborhood, you should still use some repellent," Haramis said.

Local health departments and abatement districts say they're taking action to quell the mosquito problem before it becomes a public health threat. Communities are targeting known mosquito breeding grounds, such as stagnant water at the bottom of storm drainage ditches, puddles, and even unattended backyard pools.

Oak Park began nighttime spraying for mosquitoes Tuesday, officials said, the village's first abatement effort in eight years. Wheaton and West Chicago are expected to launch another round of insect poisonings this week. Bolingbrook announced it would begin spraying Saturday morning.

The North Shore Mosquito Abatement District, which serves 13 communities in northern Cook County, has dispatched field crews to treat flood-prone areas in its 3,569 square acres of forest preserves since the end of July, said district spokesman Dave Zazra.

The neighboring Northwest Mosquito Abatement District has been receiving up to 150 calls a day from residents, Szyska said.

"The public will call in and say, 'I got eaten alive, and I put insect repellent on,'" Szyska said.

Numerous home foreclosures on Chicago's Far South Side and in southern Cook County are hampering efforts to deal with the mosquito threat, said Douglas Wright, general manager of the South Cook County Mosquito Abatement District.

"You have so many abandoned homes where pools aren't being cared for and storm gutters are not being attended to," said Wright, whose district covers 340 square miles south of 87th Street in Chicago. The district is working with municipalities to gain access to those properties, but it has slowed spraying efforts, Wright said.